Safety method for powered surgical instruments

ABSTRACT

The present disclosure provides for a surgical instrument. The surgical instrument includes a handle portion and a body portion extending distally from the handle portion and defining a first longitudinal axis. The surgical instrument includes an articulating tool assembly defining a second longitudinal axis and having a proximal end. The articulating tool assembly is disposed at a distal end of the body portion and is configured to be articulated with respect to the body portion, namely, the articulating tool assembly is movable from a first position in which the second longitudinal axis is substantially aligned with the first longitudinal axis to at least a second position in which the second longitudinal axis is disposed at an angle with respect to the first longitudinal axis. The surgical instrument also includes an articulation mechanism configured to articulate the articulating tool assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 61/234,377, filed Aug. 17, 2009, the entiredisclosure of which is incorporated by reference herein.

BACKGROUND

1. Technical Field

The present disclosure relates to a surgical instrument, e.g., a linearstapler, having an articulating tool assembly. More particularly, thepresent disclosure relates to a surgical instrument which includes amechanism for controlling and actuating an articulating surgicalinstrument.

2. Background of Related Art

Surgical instruments that include a tool assembly mounted on a distalend of a body portion of the surgical instrument for articulation arewell known. Typically, such surgical instruments include articulationcontrol mechanisms which allow an operator to remotely articulate thetool assembly in relation to the body portion of a surgical instrument.This allows the operator to more easily access, operate on, and/ormanipulate tissue.

Such articulating tool assemblies have become desirable, especially inthe endoscopic surgical procedures. In an endoscopic surgical procedure,the distal end of a surgical instrument is inserted through a smallincision in the body to access a surgical site. Typically, anappropriately sized cannula, e.g., 5 mm, 10 mm, etc., is insertedthrough the body incision to provide a guide channel for accessing thesurgical site.

Current known devices can typically require 10-60 pounds of manual handforce to clamp tissue and deploy and form surgical fasteners in tissuewhich, over repeated use, can cause a surgeon's hand to become fatigued.Gas powered pneumatic staplers which implant surgical fasteners intotissue are also known in the art. Certain of these instruments utilize apressurized gas supply which connects to a trigger mechanism. Thetrigger mechanism, when depressed, simply releases pressurized gas toclamp tissue and implant fasteners into the tissue.

Motor-powered surgical staplers are also known in the art. These includepowered surgical staplers having motors which activate staple firingmechanisms. However, these motor powered devices only provide forlimited user control of the stapling process. The user can only toggle asingle switch and/or button to actuate the motor and appliescorresponding torque to the stapler's firing mechanisms. In certainother devices, a controller is used to control the stapler, which thenpowers the clamping and fastening processes.

There is a continual need for powered surgical staplers which includevarious sensors. The sensors provide relevant feedback to feedbackcontrollers which automatically adjust various parameters of the poweredstapler in response to sensed feedback signals representative of stapleroperation, including articulation and actuation of the tool assemblies.

SUMMARY

The present disclosure provides for a surgical instrument. The surgicalinstrument includes a handle portion and a body portion extendingdistally from the handle portion and defining a first longitudinal axis.The surgical instrument includes an articulating tool assembly defininga second longitudinal axis and having a proximal end. The articulatingtool assembly is disposed at a distal end of the body portion and isconfigured to be articulated with respect to the body portion, namely,the articulating tool assembly is movable from a first position in whichthe second longitudinal axis is substantially aligned with the firstlongitudinal axis to at least a second position in which the secondlongitudinal axis is disposed at an angle with respect to the firstlongitudinal axis. The surgical instrument also includes an articulationmechanism configured to articulate the articulating tool assembly.

In one embodiment, the articulation mechanism includes one or moreswitches for activating the articulation mechanism, wherein the switchesactivate the articulation mechanism after being engaged for apredetermined period of time. The articulation mechanism may alsoinclude two or more switches which are configured to be operatedconcurrently to activate the articulation mechanism. In anotherembodiment, the articulation mechanism includes a stop switch, whichwhen actuated is configured to disable the articulation mechanism.

The surgical instrument also includes a controller and one or morelock-out sensors coupled to the articulation mechanism. The sensors areconfigured to determine when the articulating tool assembly has engagedtissue. The sensors then transmit a signal to the controller to preventfurther articulation of the tool assembly.

The controller is also configured to provide multiple commands to thearticulation mechanism for controlling the articulation of the toolassembly. The controller may provide a first articulation command to thearticulation mechanism to articulate the tool assembly in a firstdirection. The controller may then provide a second articulationcommand, which interrupts the first articulation command and signals thearticulation mechanism to articulate the tool assembly in a seconddirection.

According to one embodiment of the present disclosure, a poweredsurgical instrument is disclosed. The instrument includes a handleportion, a body portion extending distally from the handle portion anddefining a first longitudinal axis and an articulating tool assemblydefining a second longitudinal axis and having a proximal end, thearticulating tool assembly disposed at a distal end of the body portionand being movable from a first position in which the second longitudinalaxis is substantially aligned with the first longitudinal axis to atleast a second position in which the second longitudinal axis isdisposed at an angle with respect to the first longitudinal axis. Theinstrument also includes an articulation mechanism configured toarticulate the articulating tool assembly, wherein the articulationmechanism includes a motor operatively coupled to the articulating toolassembly, a controller electrically coupled to the motor and configuredto control operation of the motor and at least one switch coupled to thecontroller, wherein the at least one switch is configured to signal thecontroller to activate the articulation mechanism in response to the atleast one switch being engaged for a predetermined period of time.

According to another embodiment of the present disclosure, a poweredsurgical instrument is disclosed. The instrument includes a handleportion, a body portion extending distally from the handle portion anddefining a first longitudinal axis and an articulating tool assemblydefining a second longitudinal axis and having a proximal end, thearticulating tool assembly disposed at a distal end of the body portionand being movable from a first position in which the second longitudinalaxis is substantially aligned with the first longitudinal axis to atleast a second position in which the second longitudinal axis isdisposed at an angle with respect to the first longitudinal axis. Theinstrument also includes an articulation mechanism configured toarticulate the articulating tool assembly, wherein the articulationmechanism includes a motor operatively coupled to the articulating toolassembly, a controller electrically coupled to the motor and configuredto control operation of the motor, and a first switch and a secondswitch coupled to the controller, wherein concurrent engagement of thefirst and second switches signals the controller to activate thearticulation mechanism.

According to a further embodiment of the present disclosure anarticulation mechanism configured to articulate an articulating toolassembly is disclosed. The articulation mechanism includes a motoroperatively coupled to an articulating tool assembly, a controllerelectrically coupled to the motor and configured to control operation ofthe motor, and a first switch and a second switch coupled to thecontroller, wherein the controller activates the articulation mechanismin response to the first and second switches being concurrently engagedfor a predetermined period of time.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1 is a perspective view of a powered surgical instrument accordingto an embodiment of the present disclosure;

FIG. 2 is a partial enlarged perspective view of the powered surgicalinstrument of FIG. 1 according to an embodiment of the presentdisclosure;

FIG. 3 is a partial enlarged plan view of the powered surgicalinstrument of FIG. 1 according to an embodiment of the presentdisclosure; and

FIG. 4 is a partial perspective sectional view of internal components ofthe powered surgical instrument of FIG. 1 according to an embodiment ofthe present disclosure.

DETAILED DESCRIPTION

Embodiments of the presently disclosed powered surgical instrument arenow described in detail with reference to the drawings, in which likereference numerals designate identical or corresponding elements in eachof the several views. As used herein the term “distal” refers to thatportion of the powered surgical instrument, or component thereof,farther from the user while the term “proximal” refers to that portionof the powered surgical instrument or component thereof, closer to theuser.

A powered surgical instrument, e.g., a surgical stapler, in accordancewith the present disclosure is referred to in the figures as referencenumeral 10. Referring initially to FIG. 1, powered surgical instrument10 includes a housing 110, an endoscopic portion 140 defining a firstlongitudinal axis A-A extending therethrough, and an articulating toolassembly (e.g., end effector 160), defining a second longitudinal axisB-B extending therethrough. Endoscopic portion 140 extends distally fromhousing 110 and the end effector 160 is disposed adjacent a distalportion of endoscopic portion 140. In an embodiment, the components ofthe housing 110 are sealed against infiltration of particulate and/orfluid contamination and help prevent damage of the components bysterilization processes.

According to an embodiment of the present disclosure, end effector 160includes a first jaw member having one or more surgical fasteners (e.g.,cartridge assembly 164) and a second opposing jaw member including ananvil portion for deploying and forming the surgical fasteners (e.g., ananvil assembly 162). In certain embodiments, the staples are housed incartridge assembly 164, which is configured to apply linear rows ofstaples to body tissue either in simultaneous or sequential manner.Either one or both of the anvil assembly 162 and the cartridge assembly164 are movable in relation to one another between an open position, inwhich the anvil assembly 162 is spaced from cartridge assembly 164, andan approximated or clamped position, in which the anvil assembly 162 isin juxtaposed alignment with cartridge assembly 164.

It is further envisioned that end effector 160 is attached to a mountingportion 166, which is pivotably attached to a body portion 168. Bodyportion 168 may be integral with endoscopic portion 140 of poweredsurgical instrument 10, or may be removably attached to the instrument10 to provide a replaceable, disposable loading unit (DLU) or single useloading unit (SULU) (e.g., loading unit 169). In certain embodiments,the reusable portion may be configured for sterilization and re-use in asubsequent surgical procedure.

The loading unit 169 may be connectable to endoscopic portion 140through a bayonet connection. It is envisioned that the loading unit 169has an articulation link connected to mounting portion 166 of theloading unit 169 and the articulation link is connected to a linkage rod220 (FIG. 4) so that the end effector 160 is articulated as the linkagerod 220 is translated in the distal-proximal direction along firstlongitudinal axis A-A as discussed in more detail below. Other means ofconnecting end effector 160 to endoscopic portion 140 to allowarticulation may be used, such as a flexible tube or a tube comprising aplurality of pivotable members.

The loading unit 169 may incorporate or be configured to incorporatevarious end effectors, such as vessel sealing devices, linear staplingdevices, circular stapling devices, cutters, graspers, etc. Such endeffectors may be coupled to endoscopic portion 140 of powered surgicalinstrument 10. An intermediate flexible shaft may be included betweenhandle portion 112 and loading unit. It is envisioned that theincorporation of a flexible shaft may facilitate access to and/or withincertain areas of the body.

With reference to FIGS. 1 and 2, an enlarged view of the housing 110 isillustrated according to an embodiment of the present disclosure. In theillustrated embodiment, housing 110 includes a handle portion 112 havinga main drive switch 114 disposed thereon. The switch 114 may includefirst and second switches 114 a and 114 b formed together as a toggleswitch. The handle portion 112, which defines a handle axis H-H, isconfigured to be grasped by fingers of a user. The handle portion 112has an ergonomic shape providing ample palm grip leverage which preventsthe handle portion 112 being squeezed out of the user's hand duringoperation. Each switch 114 a and 114 b is shown as being disposed at asuitable location on handle portion 112 to facilitate its depression bya user's finger or fingers.

Additionally, and with reference to FIGS. 1 and 2, switches 114 a, 114 bmay be used for starting and/or stopping movement of drive motor 200coupled to a power source 300 (FIG. 4). In one embodiment, the switch114 a is configured to activate the drive motor 200 in a first directionto advance a firing rod (not shown) in a distal direction therebyapproximating the anvil and the cartridge assemblies 162 and 164.Conversely, the switch 114 b may be configured to retract the firing rodto open the anvil and cartridge assemblies 162 and 164 by activating thedrive motor 200 in a reverse direction. The retraction mode initiates amechanical lock out, preventing further progression of stapling andcutting by the loading unit 169. The toggle has a first position foractivating switch 114 a, a second position for activating switch 114 b,and a neutral position between the first and second positions. Similarretraction mechanisms are disclosed in a commonly-owned U.S. Pat. No.7,303,107 by Milliman et al., the entire disclosure of which isincorporated by reference herein.

The housing 110, in particular the handle portion 112, includes switchshields 117 a and 117 b. The switch shields 117 a and 117 b may have arib-like shape surrounding the bottom portion of the switch 114 a andthe top portion of the switch 114 b, respectively. The switch shield 117a and 117 b prevent accidental activation of the switch 114. Further,the switches 114 a and 114 b have high tactile feedback requiringincreased pressure for activation.

In one embodiment, the switches 114 a and 114 b are configured asmulti-speed (e.g., two or more), incremental or variable speed switcheswhich control the speed of the drive motor 200 and the firing rod in anon-linear manner. For example, switches 114 a, 114 b can bepressure-sensitive. This type of control interface allows for gradualincrease in the rate of speed of the drive components from a slower andmore precise mode to a faster operation.

The switches 114 a and 114 b are coupled to a non-linear speed controlcircuit which can be implemented as a voltage regulation circuit, avariable resistance circuit, or a microelectronic pulse width modulationcircuit. The switches 114 a and 144 b may interface with the controlcircuit by displacing or actuating variable control devices, such asrheostatic devices, multiple position switch circuit, linear and/orrotary variable displacement transducers, linear and/or rotarypotentiometers, optical encoders, ferromagnetic sensors, and Hall Effectsensors. This allows the switches 114 a and 114 b to operate the drivemotor 200 in multiple speed modes, such as continuously increasing thespeed of the drive motor 200 either incrementally or gradually dependingon the type of the control circuit being used, based on the depressionof the switches 114 a and 114 b.

FIGS. 2-4 illustrate an articulation mechanism 170, including anarticulation housing 172, powered articulation switches 174 a and 174 b,an articulation motor 132 coupled to the power source 300 and a manualarticulation knob 176. The switches 174 a and 174 b have a paddle-typeshape. The articulation switches 174 a and 174 b provide for poweredarticulation of the end effector 160 and the manual articulation knob176 provides for manual articulation. Engagement and/or translation ofthe powered articulation switches 174 a and 174 b or pivoting of themanual articulation knob 176 activates the articulation motor 132 whichthen actuates an articulation gear 233 of the articulation mechanism 170as shown in FIG. 4. The articulation gear 233 is, in turn, operativelycoupled to the linkage rod 220. More specifically, the articulationmechanism 170 moves the linkage rod 220 in a distal or proximaldirection along the longitudinal axis A-A, which imparts articulatingmotion to the end effector 160. Actuation of articulation mechanism 170causes the end effector 160 to move from its first position, wherelongitudinal axis B-B is substantially aligned with longitudinal axisA-A, towards a position in which longitudinal axis B-B is disposed at anangle to longitudinal axis A-A in either direction with respect to thelongitudinal axis A-A. The powered articulation switches 174 a and 174 bmay also incorporate similar non-linear speed controls as the clampingmechanism that is controlled by the switches 114 a and 114 b.

With reference to FIGS. 2 and 3, the housing 110 includes switch shields169 having a wing-like shape and extending from the top surface of thehousing 110 over the switches 174 a and 174 b. The switch shields 169prevent accidental activation of the switches 174 a and 174 b andrequire the user to reach below the shield 169 in order to activate thearticulation mechanism 170.

Further details of articulation housing 172, powered articulationswitches 174 a and 174 b, manual articulation knob 176 and providingarticulation to end effector 160 are described in detail incommonly-owned U.S. Pat. No. 7,431,188 to Marczyk, the contents of whichare hereby incorporated by reference in their entirety. It is envisionedthat any combinations of limit switches, proximity sensors (e.g.,optical and/or ferromagnetic), linear variable displacement transducersand shaft encoders which may be disposed within housing 110, may beutilized to control and/or record an articulation angle of end effector160 and/or position of the linkage rod 220.

As shown in FIG. 4, the instrument 10 also includes a controller 400electrically coupled to the motor 200 and various sensors disposed inthe instrument 10. The sensors detect various operating parameters ofthe instrument 10 (e.g., linear speed, rotation speed, articulationposition, temperature, battery charge, and the like), which are thenreported to the controller 400. The controller 400 may then respondaccordingly to the measured operating parameters (e.g., adjust the speedof the motor 200, control articulation angle, shut-off the power supply,report error conditions, etc.).

The controller 400 is coupled to the switch 114 and the switches 174 aand 174 b to control the motors 200 and 132, respectively. The switches174 a and 174 b may be configured to operate the articulation mechanism170 in a plurality of modes. In another embodiment, the switches 174 aand 174 b may be slidably disposed on one or more guide rails within thehousing 110. The switches 174 a and 174 b may be mechanically and/orelectrically linked such that the articulation mechanism 170 isactivated by toggling the switches 174 a and 174 b in tandem.

The switches 174 a and 174 b may be disposed about a pivot (e.g., commonor separate pivots) and may be actuated by rotation thereof about thepivot. The articulation of the end effector 160 may be accomplished byengaging and moving the switches 174 a and 174 b in a directioncorresponding to a desired articulation direction. More specifically, toarticulate the end effector 160 in a clockwise direction the switches174 a and 174 b are also moved in a clockwise direction, namely, theswitch 174 a is moved in the proximal direction and the switch 174 b ismoved in a distal direction. To articulate the end effector 160 in acounterclockwise direction the switches 174 a and 174 b are also movedin a counterclockwise direction, namely, the switch 174 a is moved inthe distal direction and the switch 174 b is moved in a proximaldirection. This configuration provides for a natural association betweenthe motion of the switches 174 a and 174 b and the end effector 169,such that the pulling one of the switches 174 a and 174 b in a proximaldirection pulls the end effector 169 toward the corresponding side andpushing one of the switches 174 a and 174 b in a distal direction pushesthe end effector 169 therefrom.

In embodiments, the switches may be engaged in the same direction, suchas for example, pushing on the switches 174 a and 174 b in the proximaldirection to articulate the end effector 169 in one direction (e.g.,clockwise) and pulling on the switches 174 a and 174 b in the distaldirection to articulate the end effector 169 in the opposite direction(e.g., counterclockwise).

In embodiments, the switches 174 a and 174 b may be independentlymovable such that the articulation mechanism 170 may be activated bytoggling either of the switches 174 a and 174 b. In either of theconfigurations, the switches 174 a and 174 b may be delayed activationswitches such that the switches 174 a and 174 b have to be engagedcontinuously for a predetermined period of time (e.g., from about 1second to about 5 seconds) to activate the articulation mechanism 170.This may be accomplished by coupling the switches 174 a and 174 b to thecontroller 400, which tracks the engagement period of time. Once theengagement period exceeds the predetermined period of time, thecontroller 400 activates the articulation mechanism 170.

In another illustrative embodiment, the switches 174 a and 174 b may beindependently movable and configured to activate the articulationmechanism 170 upon concurrent engagement thereof. More specifically,both of the switches 174 a and 174 b are toggled in the desireddirection prior to the controller 400 activating the articulationmechanism 170. The controller 400 listens for activation signals fromboth of the signals prior to activation. In one embodiment, thecontroller 400 also ensures that the engagement of both of the switches174 a and 174 b corresponds to the same desired articulation motion(e.g., pulling on the switch 174 a while pushing on the switch 174 b andvice versa) prior to signaling the motor 132. In this configuration,engagement of only one of the switches 174 a and 174 b or engagement ofthe switches 174 a and 174 b in the same direction does not trigger theactivation of the articulation mechanism. This feature may be combinedwith the delayed activation switching discussed above, such that theboth of the switches 174 a and 174 b have to be engaged concurrently fora predetermined period of time prior to the controller 400 activatingthe articulation mechanism 170.

The switches 174 a and 174 b are also configured to provide signals tothe controller 400 after an initial articulation command has beenprocessed. This allows the controller 400 to interrupt the previouslyissued command and then signal the articulation mechanism 170 to reversethe articulation motion. This feature may be combined with thedual-activation configuration discussed above, such that the reversecommand is not transmitted by the controller 400 unless both of theswitches 174 a and 174 b are engaged for a predetermined period of time.More specifically, engagement of the switches 174 a and 174 b in a firstorientation (e.g., pulling on the switch 174 a while pushing on theswitch 174 b) for a predetermined period of time signals the controller400 to articulate the end effector 160 in a first direction. Engagementof the switches 174 a and 174 b in a second orientation (e.g., pushingon the switch 174 a while pulling on the switch 174 b) for apredetermined period of time signals the controller 400 to articulatethe end effector 160 in a second direction opposite of the firstdirection.

With respect to FIGS. 2 and 4, the instrument 10 also includes a stopswitch 115 that is configured to interrupt the currently activatedarticulation command. The switch 115 is also coupled to the controller400 and engagement of the switch 115 signals the controller 400 to issuea stoppage command to the motor 132 such that current articulationcommand is interrupted. In one embodiment, the switch 115 may also beconfigured for delayed activation switching, such that the switch 115has to be engaged for a predetermined period of time prior to thecontroller 400 deactivating the articulation mechanism 170.

In addition to manual deactivation and interruption of the articulationprocesses, it is also envisioned that an automatic interlock may also beutilized. With reference to FIG. 4, the instrument 10 includes alock-out sensor 290 electrically coupled to the controller 400. Thelock-out sensor 290 is disposed within the housing 110 in proximity withthe linkage rod 220 and is configured to determine a longitudinalposition of the linkage rod 220. The lock-out sensor 290 may be any typeof a linear position sensor suitable for determining linear displacementof the linkage rod 220 such as a potentiometer, a proximity sensor(e.g., optical and/or ferromagnetic), a linear variable displacementtransducer, a shaft encoders, a Hall-effect sensor and the like. Thelock-out sensor 290 determines when the end effector 160 is engaged,i.e., when the first and second opposing jaw members of the end effector160 are grasping the tissue by measuring the displacement of the linkagerod 220. Once the linkage rod 220 is moved distally passed apredetermined point, the jaw members are engaged and tissue is graspedtherebetween. Therefore, the lock-out sensor 290 measures distaldisplacement of the linkage rod 220 and signals the controller 400 oncethe jaw members are engaged, in response to which, the controller 400prevents activation of the articulation mechanism 170 by ignoring anyarticulation commands from the switches 174 a and 174 b. Accidentalengagement of the articulation mechanism 170 may damage the instrument10 and more importantly may cause injury to the patient. The use of thelock-out sensor 290 in combination with the controller 400 prevents suchaccidental misuse of the articulation mechanism 170.

It will be understood that various modifications may be made to theembodiments shown herein. Therefore, the above description should not beconstrued as limiting, but merely as exemplifications of preferredembodiments. Although specific features of the powered surgicalinstrument are shown in some of the drawings and not in others, this isfor convenience only as each feature may be combined with any or all ofthe other features in accordance with the aspects of the presentdisclosure. Other embodiments will occur to those skilled in the art andare within the following claims.

What is claimed is:
 1. A powered surgical instrument comprising: ahandle portion; a body portion extending distally from the handleportion and defining a first longitudinal axis; an articulating toolassembly defining a second longitudinal axis and having a proximal end,the articulating tool assembly disposed at a distal end of the bodyportion and being movable from a first position in which the secondlongitudinal axis is substantially aligned with the first longitudinalaxis to at least a second position in which the second longitudinal axisis disposed at an angle with respect to the first longitudinal axis; andan articulation mechanism configured to articulate the articulating toolassembly, wherein the articulation mechanism includes: a motoroperatively coupled to the articulating tool assembly; a controllerelectrically coupled to the motor and configured to control operation ofthe motor; and at least one switch coupled to the controller, whereinthe at least one switch is configured to signal the controller toactivate the articulation mechanism in response to the at least oneswitch being engaged for a period of time having a duration in the rangeof about one second to about five seconds.
 2. The powered surgicalinstrument according to claim 1, wherein the at least one switch isengaged in a direction corresponding to a desired articulationdirection.
 3. The powered surgical instrument according to claim 1,wherein the articulation mechanism further includes a plurality ofswitches configured to be engaged concurrently to activate thearticulation mechanism.
 4. The powered surgical instrument according toclaim 1, wherein the articulation mechanism further includes a stopswitch configured to disable the articulation mechanism.
 5. The poweredsurgical instrument according to claim 1, wherein the controller isconfigured to activate the articulation mechanism in response to a firstcommand and to interrupt the activation of the articulation mechanism inresponse to a second command.
 6. The powered surgical instrumentaccording to claim 1, wherein the articulation mechanism furtherincludes a lock-out sensor electrically coupled to the controller andconfigured to determine engagement of the articulating tool assemblywith tissue, wherein the lock-out sensor prevents activation of thearticulation mechanism.
 7. A powered surgical instrument comprising: ahandle portion; a body portion extending distally from the handleportion and defining a first longitudinal axis; an articulating toolassembly defining a second longitudinal axis and having a proximal end,the articulating tool assembly disposed at a distal end of the bodyportion and being movable from a first position in which the secondlongitudinal axis is substantially aligned with the first longitudinalaxis to at least a second position in which the second longitudinal axisis disposed at an angle with respect to the first longitudinal axis; andan articulation mechanism configured to articulate the articulating toolassembly, wherein the articulation mechanism includes: a motoroperatively coupled to the articulating tool assembly; a controllerelectrically coupled to the motor and configured to control operation ofthe motor; and a first switch and a second switch coupled to thecontroller, wherein concurrent engagement of the first and secondswitches for a period of time of about one second to about five secondssignals the controller to activate the articulation mechanism.
 8. Thepowered surgical instrument according to claim 7, wherein the firstswitch and the second switch are engaged in a direction corresponding toa desired articulation direction.
 9. The powered surgical instrumentaccording to claim 7, wherein the articulation mechanism furtherincludes a stop switch configured to disable the articulation mechanism.10. The powered surgical instrument according to claim 7, wherein thecontroller is configured to activate the articulation mechanism inresponse to a first command and to interrupt the activation of thearticulation mechanism in response to a second command.
 11. The poweredsurgical instrument according to claim 7, wherein the articulationmechanism further includes a lock-out sensor electrically coupled to thecontroller and configured to determine engagement of the articulatingtool assembly with tissue, wherein the lock-out sensor preventsactivation of the articulation mechanism.
 12. An articulation mechanismconfigured to articulate an articulating tool assembly, the articulationmechanism comprising: a motor operatively coupled to an articulatingtool assembly; a controller electrically coupled to the motor andconfigured to control operation of the motor; and a first switch and asecond switch coupled to the controller, wherein the controlleractivates the articulation mechanism in response to the first and secondswitches being concurrently engaged for a period of time having aduration in the range of about one second to about five seconds.
 13. Thearticulation mechanism according to claim 12, wherein the first switchand the second switch are engaged in a direction corresponding to adesired articulation direction.
 14. The articulation mechanism accordingto claim 12, further comprising a stop switch configured to disable thearticulation mechanism.
 15. The articulation mechanism according toclaim 12, wherein the controller is configured to activate thearticulation mechanism in response to a first command and to interruptthe activation of the articulation mechanism in response to a secondcommand.
 16. The articulation mechanism according to claim 12, furthercomprising: a lock-out sensor electrically coupled to the controller andconfigured to determine engagement of the articulating tool assemblywith tissue, wherein the lock-out sensor prevents activation of thearticulation mechanism.